Z8FMC16100 Series Flash MCU
Product Specification
239
Internal Precision Oscillator
The Internal Precision Oscillator (IPO) is designed for use without external components.
The IPO comes factory trimmed a ±4% frequency accuracy over the operating tempera-
ture and supply voltage range of the device. IPO features include:
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On-chip RC oscillator that does not require external components
Trimmed to ±4% accuracy
Target output frequency of 5.5296MHz
Trimming possible through Flash option bits with user override
Can eliminate crystals or ceramic resonators in applications where high timing accura-
cy is not required.
Operation
The internal oscillator is an RC relaxation oscillator that has had its sensitivity to power
supply variation minimized. By using ratio tracking thresholds, the effect of power supply
voltage is cancelled out. The dominant source of oscillator error is the absolute variance of
chip-level fabricated components, such as capacitors. Two 8-bit trimming registers, incor-
porated into the design, allow compensation of absolute variation of oscillator frequency.
Once calibrated, the oscillator frequency is relatively stable and does not require subse-
quent calibration.
By default, the oscillator is configured through the Flash Option bits. However, the user
code can override these trim values as described in Trim Option Bits section on page 223.
PS024604-1005
P R E L I M I N A R Y
Operation
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